Root pressurisation may cause stomatal re-opening in plants growing in drying soil via a mechanism, which is aba dependent

M. W., Puteri Edaroyati and Bacon, M. A. and Davies, W. J. (2009) Root pressurisation may cause stomatal re-opening in plants growing in drying soil via a mechanism, which is aba dependent. Journal of Tropical Plant Physiology, 3. pp. 72-82.

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Abstract

Stomatal closure was induced in two cultivars of tomato (Lycopersicon esculentum L. cv. Solairo and Alisa Craig) by allowing the plants to dry the soil in which they were rooted. Sealing the roots within a root pressure vessel and applying a pneumatic pressure reversed this restriction in stomatal conductance. Pressurisation resulted in a significant decline the xylem sap concentration of abscisic acid within one of the cultivars, which was consistent with stomatal reopening. We propose a mechanistic explanation of stomatal re-opening based on a pressurisation-induced decrease in abscisic acid concentrations around the active sites for stomatal closure, and an appreciation of the existence of apoplastic bypasses for ABA. Our results cast doubt on the conclusions of similar investigations using root pressurisation, which argue for a dominant role for leaf water status in the control of gas exchange in plants.

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